The present invention is related to a device for varying a cylinder""s effective diameter which for example can be arranged in a folding apparatus for processing a web of material.
EP 0 249 874 discloses an improved stacking method and apparatus. With this device signatures are stacked into a plurality of bundles prior to further processing thereof. The signatures are conveyed to a stacker by an infeed conveyor. The stacker places counted stacks of signatures on a turn table from where the individual bundles are ejected by ejecting means after stacking. The infeed conveyor is operated at a selected speed. The stacker, the turn table, and the ejecting means are operated at a speed which is a function of the rate of speed of the signatures delivered by the infeed conveyor to the stacker. This solution comes along with a V-shaped roller surface to apply a V-shaped profile to stiffen the signatures to obtain advantageous handling characteristics.
EP 0 523 346 A1 is related to an apparatus for cutting and transporting a paper web in a folding apparatus of a printing press. The apparatus disclosed in this document comprises a pair of cutting cylinders for cutting web sections from the web and a transporting device for transporting the web sections away from the cutting cylinders. The first cutting cylinder has at least one cutting anvil and the second cutting cylinder has at least one cutting knife which meets the cutting anvil at a nip between the cutting cylinders to cut the web moving through the nip. A plurality of strips are supported on the first cutting cylinder and a plurality of strips are supported on the second cutting cylinder. The strips have positions on the cutting cylinders in which they impress a temporary reinforcing profile onto each newly formed leading portion of the web when the strips move through the nip. At least one smoothing surface is supported on the first cutting cylinder and at least one smoothing surface is supported on the second cutting cylinder. The smoothing surfaces have positions on the cutting cylinders wherein the smoothing surfaces remove the temporary reinforcing profile from the leading portion of the web on the smoothing surfaces move through the nip.
However, the solution according to EP 0 523 346 A1 discloses an adhesive bonding of said strips onto the respective cylinders surfaces which causes problems in replacing worn out strips on said cylinders surfaces.
The problem of changing the effective outer diameter of a cylinder has been addressed by gluing on Velcro brand hook and loop fastener sections on the cylinders surfaces, or mylar-coating to increase the respective cylinder diameter. Another approach was using air or foam cushions to squeeze the running web of material into other rotating rolls. Once these materials have been mounted on the respective cylinder surface, it is difficult to remove them from the cylinder surface as they are bonded onto those surfaces. Thus, the exchange of this materials comes along with the difficulty of dismounting the initially bonded materials after months of operation.
In view of the prior art cited and the problems encountered in the technical field, it is accordingly an object of the present invention to facilitate the change of a cylinders"" effective diameter.
Another object of the present invention is to provide a quick interchange device to change a cylinder""s gain according to the requirements.
A still further object of the present invention is to provide a surface jacket for a cylinder covered with a material having elastic properties creating a semi-compressible cylinder""s surface.
According to the present invention, a device for varying the effective diameter of a cylinder comprises:
a shell member removably mounted on a surface of a cylinder,
said shell member having a base plate and an elastic material arranged on said base plate allowing for a compressible surface gain.
This solution offers several advantages such as preserving a variety of surface shells, each having a coating with different material properties to allow for a strong squeeze of the web of material in the nip or a lower squeeze of the web of material in the respective nip. According to the thickness of the web of material to be processed, the thickness of the elastic material on the base plate can be chosen. Since the shell member is removably mounted on the cylinders surfaces, a quick interchange is feasible now, which according to the bonded material was not easy to achieve with the solutions already known in the field. In a folder apparatus wherexe2x80x94among other applicationsxe2x80x94the present invention can be used different amounts of gain be adjustedxe2x80x94just as is required for the respective job. This is extremely important for newspaper applications and wherever there else is an extreme time pressure.
According to further details of the present invention, said cylinders include lock-up devices for the shell members respective trailing edge. Furthermore, said cylinders are equipped with a quick mounting device for the respective shell members""leading edge. Said quick mounting device may be embodied by a hook-shaped edge of the part of the cylinder forming the wall of a gap in which said lock-up device is arranged. Preferably the width of said base plate in lateral direction thereof corresponds to the width of a printing plate suitable for newspaper applications. The width of said shell member is approximately 16.00 inches. The base plate may be manufactured of aluminium or steel having a higher degree of durability.
By means of the aforementioned lock-up device for the removable shell member said shell members are quickly removable from respective cylinders surface. Thus, on the respective base plate of said shell members different coatings having different elastic properties may be applied. For each job the required shell members easily are chosen, dismounted and mounted on the cylinder, respectively. The elastic material applied as a coating of uniform or varying thickness on the respective base plate may be sprayed foam or a hook and loop fastener material such as Velcro. A coating of a reinforced rubber material is conceivable as well. The elastic material may be made of a duro-elastic material or an abrasive cloth.
Said elastic material may be applied to the base plate so as to fully cover the entire surface thereof. Said elastic coating can be arranged in strips as well so as to form recesses there between, where there is no elastic material.
Said lock-up device for the shell members may be arranged within a gap on the circumference of said cylinders and comprise a tensioning member for said trailing edge of said shell member. The tensioning member is arranged so as to be pivotable about an axis.
Said shell members being quickly mounted and dismounted on or from a cylinders body, respectively, may be arranged on cylinders or pairs of cylinders cooperating with each other. Said cylinders may form a part of a folder apparatus design.